Seats

So, I ran into a problem... Af least for the time being. Recently got all new legendary vinyls and pads... Unfortunately the passenger seat is not a 66/67 seat. Does anyone know how close the frames are? They are the correct size, but obviously the 68 doesn’t have the wrap around metal backs. I have another back, but not sure if it works. I’ve had a busy work week so I haven’t torn into them to find out. Figured someone here may have had to make it work